I've got a Shimano Sora on a 8-gear cassette, and have odd behavior and skipping, shifting under stress.
This started with a trip to the mechanic for a tune up which replaced the chain. I had some skips so I replaced the cassette. Still more skipping, a second trip to the mechanic didn't do much good.
I tried adjusting it myself and found some odd behavior:
- Had to adjust the H screw way out, and it doesn't seem to reliably return to the same spot while pedaling (while working on it).
- When I start at the smallest gear and shift to the largest, everything looks perfectly aligned.
- When I start at the largest gear and shift to the smallest, the first click does almost nothing. The second goes to the 7th gear, third click to the 6th... and the seventh click skips from the 3rd gear to the first.
- After all this, it doesn't seem to move back into the original position without a little push.
Any ideas on what's going wrong here? It seems like tension pulling the chain out is not sufficient, but I don't see any adjustment for that.
Am I barking up the wrong tree?